Electrical incandescent lamp.



H. GERDIEN & IVI. VON PIRANI.

IELI-ICTRICIII.y INCANDESCENT LAMP. APPLICATION FILED FEB. I6. 1915.

19193 Patented May 18, 1915.

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J/ GAS WILLI/V6 5.45 FILLING UNTTED sTATEs PATENT OFFICE.

HANS GERDIEN, 0F BERLIN-SCHMABGENDORF, AND MARCELLO von PIRAN I, 0F BERLIN- WILMERSDORF, GERMANY, ASSIGNORS T0 SIEMENS & HALSKE A.G., 0F BERLIN, GERMANY, A CORPORATION 0F GERMANY.

ELECTRICAL INCANDESCENT LAMP.

Specication of Letters Patent.

Patented May 18, 1915.

T0 all whom, it may concern Be it known that we, HANS GERDIEN, a German citizen, and resident of Berlin- Schmargendorf, Germany, and MARCELLO voN Pimm, an Italian citizen, and resident of erlin-lvilmersdorf, Germany, have invented certain new and useful Improvements in Electrical Incandescent Lamps, of which the following is a specification.

This invention relates in general to an electric lamp with a gas filling and an incandescent filament. The filling more particularly may consist of any proper gas, or mixture of gases, for instance mercury vapor mixed with other gases such as argon or nitrogen. In an incandescent lamp of this latter kind the mercury vapor will be generated in the well known manner by the heat radiating from the filament which is preferably made in concentrated form such as in the form o f a spiral.

Our present invention in brief consists therein that we arrange a separating wall or similar device preferably above or around the filament of the lamp for the purpose of providing a chamber or space around the filament which space is more or less separated from the remaining space within the bulb. This separating wall moreover is so constructed that it will not result in an absolutely tight separation between the two spaces in the lamp bulb, but in such a manner that it will permit an exchange of the gases between said spaces only to a limited extent. For this purpose the separating wall may be provided with slots or holes enabling the passage of gas from one into the other space. Our incandescent lamp by reason of the employment of the aforementioned spaces will operate in such a manner that the ascending or upward whirling of gas, for instance of the hot mercury vapor which is generated by evaporation, will be prevented. Thus in case mercury is employed, inthe lower space or chamber for the filament an atmosphere will be generated which consists mainly of pure mercury vapors, while the other gas which is possibly present will be pushedv into the upper space of the bulb; in this manner the mercury vapor will essentially be kept within the lower space. In the incandescent lamp according to our present invention the separating wall or similar device will also be heated bythe filament,

so that in case mercury vapor is employed as filling, there will only little quantities of mercury be able to condense upon said wall. By this arrangement it will also be prevented that mercury after being condensed will fall down in drops upon the filament.

The advantages which are secured by our present invention consist mainly therein that the filament will burnin a relatively quiet and rather pure atmosphere of mercury vapor. Since 'mercury vapor is a much poorer conductor of heat and electricity than other indifferent gases, for instance nitrogen, argon, etc., the filament in our present incandescent lamp can therefore be much better utilized than has heretofore been possible.

The employment of the separating wall or similar device which we have so far described, is not limited to lamps containing a filling of mercury vapor. In particular we have found that this arrangement is also of great importance, if no mercury at all is contained in the filling, that is if the same con sists of a gas or gases other than mercury vapor. In this case by said separating wall or similar device an economizing effect is secured similar to that in the so-called economizing are lamps.

Our invention will be more fully understood by reference to the accompanying drawing which shows two forms of lamps according to our invention and of which- Figure 1 shows an incandescent lamp with mercury vapor as a filling which is provided with the aforementioned separating wall, and F ig. 2 is al modification of the lamp of Fig. 1,"which modification consists mainly therein that the filling contains no mercury and that the separating wall of Fig. l is so constructed that it will act as economizing device as above mentioned.

In the drawing a represents the incandescent filament which is preferably made from metal and which is wound up in the manner of a spiral, b is the bulb of the lamp, c the mercury contained therein and d the separating wall which is arranged above the filament.

In order to establish a communieationb tween the space above the separating wall and that below the same, this wall may for instance be provided with openings which of the leading-inwires carrying the vfilament or near the bulb, ,so thatlan exchangefof-v gases will be enabled toV a certain extent be@ tween said two spaces. The separating wall d moreover is mounted above the filament and so closely thereto that it will be heated by the'same.

In Fig. 2 the separating wall of F 1g. 1 1s replaced by the economizing device d1 which may either be of the form of a plate or of an inverted bowl, as shown in the drawing. In addition to this economizing device a further plate e may be employed below the filament which may be of transparent material such as quartz-glass, mica or a similar substance. The incandescent iilament will therefore be fully surrounded by a chamber which is formed by the wall d, and the plate e. In the same manner as in F ig. 1 holes f may be provided at proper points, for instance as indicated in the drawing for permitting a vlimited exchange of gases between the space of the filament and the remaining part of the glass bulb:

Having thus described our invention we claim as new and desire to secure by Letters Patent of the United States 1. In an electric incandescent lamp the combination of a bulb, a gas lling, -a laf ment mounted within said bulb, and a separating wall mounted near said filament and dividing the interior of said bulb into two' spaces, said wall being adapted topermit a limited exchange of gas between said spaces.

2. In electric incandescent lamp lthe combination ,of a bulb, a gas lling, a filament `mounted within said bulbfan economizing device partly or Wholly surrounding f said filament, said economizing device forming a-fspace or chamber around said filamentand being adapted to permit a limited exchange of gas between saidspace or chamber and the remaining `part of the space within saidy bulb.

3. In` an electric incandescent lamp the combination of a bulb, a' gas iilling containing mercury, a filament mounted within said bulb, and a separating wall mounted above` said filament and dividing the interior of lsaid bulb intotwo'spaces, said wall being adapted to permit a limitedl exchange of gas between said spaces.

4. In an electric incandescent lamp the combination of a bulb, a gas filling containingvmercury, akflament mounted within said 'HANS GERDIEN. v MARCELLO voN PIR-ANI. Witnesses:

WOLDEMAR HAUPT, HENRY HASPER. 

